The present invention provides deicing compositions which are environmentally benign, a process for producing the composition from certain waste process streams, and methods of deicing and/or anti-icing.

The present invention relates to a deicing fluid composition. More particularly the present invention relates to a deicing fluid composition which is environmentally benign. Most particularly the present invention relates to an environmentally benign deicing fluid composition which is obtained from various industrial waste streams or from the pure components.
Freezing point lowering compositions are in widespread use for a variety of purposes, especially to reduce the freezing point of an aqueous system so that ice cannot be formed or to melt formed ice. Generally, freezing point lowering compositions depend for their effectiveness upon the molar freezing point lowering effect, the number of ionic species which are made available and the degree to which the composition can be dispersed in the liquid phase in which the formation of ice is to be precluded and/or ice is to be melted.
The most pervasive of the commonly used products for deicing are common salt, calcium chloride and urea, with common salt (sodium chloride) being the least expensive and most commonly used. Common salt is widely used to melt ice on road surfaces and the like. In this manner the salt forms a solution with the available liquid in contact with the ice and thereby forms a solution with a lower freezing point than the ice itself so that the ice is melted. Chloride salts however suffer from relatively severe drawbacks, such as the harmful effects on surrounding vegetation by preventing water absorption in the root systems, and its corrosive effects on animal skin such as the feet of animals, clothing, roadways and motor vehicles.
Other inorganic salts are also known to be useful as freezing point lowering agents such as magnesium chloride, potassium phosphates, sodium phosphates, ammonium phosphates, ammonium nitrates, alkaline earth nitrates, magnesium nitrate, ammonium sulfate, alkali sulfates.
Typical of solutions of low freezing points include brines, ethylene glycol and propylene glycol solutions. Brines are used to transfer heat at temperatures below the normal freezing point of water, and the ethylene glycol solutions are well known for use as coolants for automobiles and the like in regions in which the temperature may fall below the normal freezing point of water. Ethylene and propylene glycols are used in relatively large quantities at major airports in northern climates in order to keep air traffic flowing during inclement weather. The fluids are generally applied to the wings, fuselage and tail of aircrafts as well as the runways to remove ice. However, these glycol compounds likewise have environmental drawbacks and can be detrimental to sewage treatment processes.
Other prior art deicing fluids such as alcohols have toxic effects and high volatility particularly in the low molecular weight range and may be the cause of offensive smell of fire danger. Furthermore, mono- and polyhydric alcohols oxidize in the presence of atmospheric oxygen to form acids, which can increase corrosion of materials.
Due to the problems associated with deicing agents as described above there have been attempts to prepare even more deicing agents. For, example, Kaes, U.S. Pat. No. 4,448,702 discloses the use of a freezing-point lowering composition and method which calls for the addition of a water soluble salt of at least one dicarboxylic acid having at least three carbon atoms, such as a sodium, potassium, ammonium or organoamine salt of adipic, glutaric, succinic or malonic acid.
Peel, U.S. Pat. No. 4,746,449 teaches the preparation of a deicing agent comprising 12-75% acetate salts, trace-36% carbonate salts, 1-24% formate salts and 1-32% pseudolactate salts which is prepared from a pulp mill black liquor by fractionating the black liquor into a molecular weight fraction and concentrating the collected low molecular weight fraction to produce the deicing agent.
U.S. Pat. No. 4,960,531, teaches that small amounts of methyl glucosides, i.e. less than 10%, can be employed as a trigger to conventional salt deicers.
However, all of these disclosures still require the presence of salts. Accordingly there still exists in the art a need for a deicing and/or anti-icing agent which is environmentally benign and relatively inexpensive to obtain.
Accordingly the present invention comprises a deicing and/or anti-icing agent which is environmentally benign and can be produced from relatively inexpensive feedstocks. In one embodiment of the present invention the deicing agent comprises a water soluble solution of hydroxycarboxylic acid based esters which are preferably prepared from waste process streams such as from the admixture of components of a pulp mill black liquor with distiller grain solubles and/or whey; the acid treatment of pre-distilled wood, agricultural and/or milk fermentation; the alcoholysis of distiller grain solubles or any combination thereof.
The compositions of the present invention can be applied to a wide variety of surfaces, particularly metallic and non-metallic surfaces of aircraft, which prevents icing, removes frozen water from the surface and prevents its reformation. The invention provides for a deicing composition which can be used on airplanes, runways, bridges, streets and the like. Further, the compositions can be used in heat transfer applications and to applications in which it is vital to maintain a liquid in the unfrozen state, e.g., as in a fire extinguisher. Additionally, the present invention provides for an anti-icing composition which can be applied to a surface, such as bridges, prior to the onset of icing conditions in order to prevent icing from occurring.
The present invention further provides deicing and/or anti-icing agents which are prepared from the pure components, hydroxycarboxylic acid esters, hydrocarbyl aldosides, and or combinations thereof. In one further embodiment of the present invention there is provided a method for deicing and/or anti-icing a surface, the method comprising applying to the surface a composition comprising (a) a deicing and/or anti-icing agent comprising at least about 15 weight percent of a hydrocarbyl aldoside and (b) water. In another further embodiment, there is provided a deicing and/or anti-icing agent composition comprising (a) a hydroxycarboxylic acid salt, (b) a hydrocarbyl aldoside and (c) water.
The present invention provides a novel composition useful as a deicing agent and/or an anti-icing agent and a novel method of preparing the deicing and/or anti-icing agents.
The deicing agents of the present invention comprise a hydroxycarboxylic acid ester, a hydrocarbyl aldoside, or both.
Hydroxycarboxylic acid esters are well known to those of ordinary skill in the art and typically comprise hydroxyformate, hydroxyacetate, hydroxypropionate, hydroxybutyrate, hydroxylaurate, hydroxypalmitate, hydroxyoleate, hydroxybenzoate as well as others. Preferred for use in the practice of the present invention are deicing agents comprising xcex1-hydroxypropionate type esters such as alkyl lactates.
Hydrocarbyl aldosides are well known to those of ordinary skill in the art. Preferably the hydrocarbyl aldosides comprise alkyl aldosides and/or sorbitols.
The alkyl aldosides can be prepared by a continuous alcoholysis process for making mixed aldoside from polysaccharides, and more particularly, for making mixed alkyl glycosides directly from starch, as described in U.S. Pat. No. 4,223,129. A further process of producing aldosides for use in the practice of the present invention is described in U.S. Pat. No. 4,329,449.
Typical of the alkyl aldosides useful in the practice of the present invention are alpha-methyl glucoside, beta-methyl glucoside, methyl furanosides, methyl maltosides, methyl maltotriosides, mixtures thereof and the like.
In addition to the hydroxycarboxylic acid esters and/or hydrocarbyl aldosides, a wide variety of other components may be included in the deicing and/or anti-icing compositions of the present invention. Along with the free hydroxycarboxylic acid, preferably these include water soluble anionic hydroxycarboxylic acid salts. Generally these components may be added to the deicing and/or anti-icing compositions of the present invention or they are present in or are derived from the process waste streams from which the compositions of the present invention may be obtained.
Also, it is contemplated herein that anionic hydroxycarboxylic acid salts alone or with amino acids and/or water soluble salts of dicarboxylic acids having at least three carbon atoms, preferably selected from adipic, succinic, glutaric and malonic acids may also be included, but are not necessary to the practice of the present invention. These can be added separately such as through the addition of pulp mill black liquors or via alkali additions to hydroxycarboxylic acid containing compositions.
The deicing agents may be prepared from the pure chemical ingredients. For instance, a solution of 25% H2O/10% sodium lactate/65% ethyl lactate was found to have no crystal formation at a temperature of xe2x88x9250xc2x0 C.
However, it is contemplated by the present invention to obtain the deicing agents of the present invention from any of a number of industrial waste streams which comprise a water soluble solution of hydroxycarboxylic acid, since lactic acid as it occurs in dilute fermentation liquors is inexpensive. The purification of this material is difficult due to its similarity in solubility characteristics to water as the presence of impurities such as dextrins, proteins and unfermented sugars. For instance, the present invention contemplates the use of waste stream selected from the group consisting of a grain stillage, a wood stillage, agricultural or milk fermentation and mixtures of any of the foregoing. Generally, the components of the present invention are present in or are derived by alcoholysis of the process waste streams. Typically these waste streams include components such as lactic acid fractions and low molecular weight sugars as sorbitols, maltoses and glucoses.
By subjecting the waste streams to alcoholysis (with an alkyl alcohol) under conditions such as reacting with an alkyl alcohol in the presence of a cation exchange material or other acid, or the addition of an alkyl alcohol to a heated fermentation liquor as taught in Ind. Eng. Chem., 38, pg. 228, 1946 by E. M. Filachione and C. H. Fisher, at least some of the hydroxycarboxylic acids present are converted to the hydroxycarboxylic acid based esters and at least some of the sugars are converted to glucosides, thereby improving the overall acidity of the material. For instance, ethanol treatment of a typical agricultural fermentation waste stream comprising lactic acid and glucose would be partially converted to ethyl lactate and ethyl glucoside. The use of the alcoholysis process aids in increasing the concentration of the glycosides and hydroxycarboxylates, thereby providing an improved product.
For example, components of the present invention can include, but are not limited to: ethyl lactate, glycerol, glycol lactate, ethyl glycinate, ethyl levulinate, ethylenecarbonate, glycerin carbonate, pipecolic acid, tetrahydrofurfuryl acetate, tetrahydrofurfuryl tetrahydrofuroate, sorbitol, glucose glutamate, methyl glucosides, acetals and ketals of glycerol such as 2,2-dimethyl-1,3-dioxolane-4-methanol and salts thereof and the like.
As discussed above, although not critical for the present invention, the compositions of the present invention may further comprise high solubility salts in combination with the hydroxycarboxylates and glucosides. For example, useful salts could include, but are not limited to: hydroxycarboxylic acid salts (including cesium, sodium, potassium, calcium and magnesium salts) such as sodium lactate; acetate salts such as cesium acetate, sodium acetate, potassium acetate; formate salts such as sodium formate; citrate salts such as sodium citrate; amino acids and their salts such as lysine glutamate, sodium pyrrolidone carboxylate and sodium glucoheptonate; dicarboxylic acids salts such as sodium and potassium salts of adipic, glutaric, succinic and malonic acids; lignin components such as lignin sulfonate; boric acid and its salts, glycerin and the like.
Glycols such as propylene glycol, ethylene glycol may also be employed with the compositions of the present invention where desired.
The amount of the acid components, i.e. the hydroxycarboxylic acid esters, hydroxycarboxylic acid salts, lignins and glucosides, which are present in the compositions of the present invention may vary widely and still provide the improved freezing point lowering effect. Preferably, however, the compositions of the present invention comprise a total weight of acid components ranging from about 10 to about 75 weight percent, more preferably from about 20 to about 75 weight percent and most preferably from about 30 to about 75 weight percent, based on the weight of acid and water combined.
The compositions of the present invention are considered non-toxic and readily breakdown, even at low temperatures, in the natural environment without any significant adverse effects. Moreover, the compositions of the present invention are considered to have lower Biological Oxygen Demand (BOD) requirements than comparable de-icers, and a lesser amount of the composition of the present invention (higher water concentration) is required to prevent ice formation at a particular ambient air temperature or quantity of ice. Since the concentration of an anti-icer that is applied should be sufficient to prevent significant ice formation under reasonable conditions much smaller material usage for the composition of the present invention at particular outside air temperatures and precipitate rates results.
In the methods of the present invention, the deicing and/or anti-icing compositions of the present invention are combined with water and applied, such as by spraying, onto the surface desired to be treated. In the case of deicing, the surface already has ice formed thereon, and the deicing compositions of the present invention melt the ice already formed and are further effective in preventing additional ice formation. In the case of anti-icing, upon learning of a weather forecast which predicts possible dangerous icing conditions, the roads and bridges or other surfaces can be pretreated with the anti-icing compositions of the present invention in order to prevent ice formation on the surface.
In one embodiment of a method of the present invention where the deicing and/or anti-icing agent includes a hydrocarbyl aldoside without a hydroxycarboxylic acid ester component, the amount of hydrocarbyl aldoside employed to obtain the benefits of the present invention is at least about 15 weight percent based on the weight of the deicing and/or anti-icing agent (not including water) and can comprise up to 100 weight percent. Typically, however the amount of hydrocarbyl aldoside is from about 15 to about 90 weight percent, such as from about 30 to about 90 weight percent, and more particularly from about 50 to about 75 weight percent.
The following examples are provided for illustrative purposes and are not to be construed to limit the scope of the claims in any manner whatsoever. Unless otherwise indicated, melting points were determined using a Differential Scanning Calorimeter (DSC). Scans were conducted from xe2x88x92160xc2x0 C. up to 30xc2x0 C. at 10xc2x0 C. per minute on a 1 mg sample taken from a 20 g mixture. The complete melt point was utilized.

Environmentally benign anti-icing or deicing fluids


A suspension arrangement for suspending an air conditioning system from an aircraft airframe structure includes a first suspension unit including plural individual suspension rods, and a second suspension unit including a base frame supported from vertical carrier members. Upper ends of the carrier members are secured to load-carrying suspension points of the airframe structure. Upper ends of the suspension rods are secured to load-introduction points on the base frame. Bottom ends of the suspension rods are secured to suspension points on the components of the air conditioning system. The frame provides a greater number and variety of suspension locations to accommodate a greater number of suspension rods for suspending the air conditioning system, with a smaller number of vertical carrier members being secured to corresponding suspension points on the airframe structure. An intermediate mounting support arrangement may further be provided between the suspension rods and the suspension frame.

The invention relates to a suspension arrangement for supporting an air conditioning system or a so-called air generation unit within the fuselage of an aircraft, and especially a high capacity commercial passenger transport aircraft.
There are various arrangements known in the art for supporting air conditioning systems, i.e. so-called air conditioning packs or air generation units, in the fuselage of an aircraft. Especially in high capacity passenger aircraft, of which the fuselage interior space is divided into an upper deck and a lower deck, it is known to support an air conditioning system on the aircraft structure, mainly in either one of two technologically different manners or concepts. The first concept, which applies especially to aircraft with an integrated air-supported air conditioning system, involves suspending the air conditioning system from the aircraft fuselage ceiling structure using suspension rods. The second concept involves supporting the air conditioning system standing on the cabin or freight compartment floor.
In the first concept of suspending the air conditioning system using suspension rods, the first step is to define the necessary force introduction points statically on each one of the various components of the air conditioning system and similarly also on the aircraft airframe structure in order to achieve the required weight-bearing suspension support as well as the necessary degree of safety. Namely, the suspension arrangement must be strong and secure enough, and provide a sufficient safety margin, to comply with applicable aviation regulations, which are especially stringent for overhead suspended installations. So-called suspension rods are used as the connection and force bearing elements. These rods must be specially designed and fabricated with a high precision tolerance to the specific required installation length for each suspension point, even though the rods allow a small degree of length adjustment.
In order to install this suspension arrangement in the aircraft, all of the rods are first individually pre-mounted on the defined force introduction points or load-bearing points on the aircraft airframe structure, and then the various individual air conditioning components or devices of the air conditioning system are installed and suspended on the bottom ends of the suspension rods. In this regard, the various suspension rods must be individually adjusted. In order to accommodate different patterns of the load-introduction points on the air conditioning system in comparison to the load-introduction points on the aircraft airframe structure, the individual suspension rods are arranged at various angles and with various lengths, resulting in a rather complicated and time consuming installation process.
Nonetheless, such a suspension arrangement, which is used, for example, in the known Airbus A319, A320, A321, A330 and A340 aircraft, is a very advantageous manner of installing and supporting the air conditioning system. Namely, during the installation, this suspension arrangement provides a high degree of flexibility, because essentially every load-bearing structure of the aircraft airframe can be utilized as a possible suspension point for a respective component of the air conditioning system. It is also possible to install the air conditioning system in the area enclosed within the belly fairing, namely outside of the main pressurized aircraft fuselage, whereby the air conditioning system is supported below the aircraft airframe structure, without using up any of the available space or volume within the aircraft structure itself.
The above mentioned second concept for supporting an air conditioning system is used, for example, in the known Airbus A300 and A310 aircraft, and involves mounting and securing the air conditioning system on a corresponding statically determined loadable area of a floor within the aircraft structure. While this installation concept is simpler than the above described first concept using suspension rods, this second concept also suffers certain disadvantages. Foremost, this installation requires a direct mechanical connection of the air conditioning system onto a strong, rigid, load-bearing floor structure within the aircraft fuselage itself. This, of course, limits the flexibility of the Id location at which the air conditioning system can be installed, and also necessarily reduces or encroaches on the available cabin volume and freight compartment volume that is available within the aircraft fuselage. Any attempt to install an air conditioning system in this manner in any area other than a pre-existing load-supporting floor of the aircraft structure would carry with it severe weight penalties, because it would be necessary to build an additional load-bearing floor area.
Neither of the two above described conventional air conditioning system installation and support concepts are well suited to installing an air conditioning system in the high capacity multi-deck passenger transport aircraft now under development, whereby it is desired to install the air generation units (AGUs) in extremely high areas within the aircraft fuselage structure and/or at locations that will only partially reduce the available cabin or freight volume available within the aircraft fuselage. Particularly, it is desired to install the air generation units at locations where the remaining volume within the fuselage above or below the respective air conditioning system will still be usable, for example as passenger cabin space or freight and cargo hold space. It is also important that the installation does not significantly add to the weight of the overall aircraft, and is simple and economical to carry out.
In view of the above, it is an object of the invention to provide a suspension arrangement for supporting an air conditioning system or so-called air generation unit (AGU) in a high capacity commercial transport aircraft in a manner that is simple and economical to install, comparatively light in weight, and high in load supporting strength and crash worthiness or safety in an accident situation. It is a further object of the invention to provide such a suspension arrangement for suspending an air generation unit in an extremely high and difficult to access installation space in the lower aircraft fuselage area. Moreover, the installation shall be such that the remaining volume above or below the air conditioning system shall still be usable as passenger space, cargo and freight space, or storage space. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a suspension arrangement for suspending an air conditioning system (or other system unit) in an aircraft. The suspension arrangement includes distinct first and second securing units or suspension mounting units. The first suspension mounting unit comprises plural suspension rods that are each secured at their bottom end to a respective component of the air conditioning system and extend vertically or substantially vertically upwardly from the air conditioning system. The second suspension mounting unit comprises a suspension frame that is secured to defined force introduction and support locations on the aircraft airframe structure below or within the outer enclosure of the aircraft fuselage. The respective upper ends of the suspension rods of the first suspension mounting unit are secured to defined force introduction and support locations on the suspension frame.
By providing these two distinct suspension mounting units with distinct functions, the invention achieves the above described advantages. The installation is very flexible and adaptable, yet simple and economical to carry out. The suspension frame provides a standardized array of load-introduction or suspension points, preferably on a single suspension plane, from which the suspension rods of the other suspension mounting unit may be secured and suspended. Thereby, the suspension frame is flexibly adaptable to different configurations of the aircraft fuselage structure or airframe structure at different locations at which the air conditioning system may be installed. On the other hand, the suspension rods more simply need to be connected only between the specialized load-introduction or suspension points on the various components of the air conditioning system at the respective lower ends of the suspension rods, while the upper ends of the suspension rods can be easily secured to the standardized or pre-established array of suspension points provided on the suspension frame. The array of suspension points on the suspension frame can already be adapted to generally match the locations of the suspension points of the air conditioning system. It is thus no longer necessary for the suspension rods to achieve the accommodation between differing patterns and locations of suspension points on the air conditioning system and on the aircraft air-frame structure respectively.

Suspension for air generation units in aircraft


Lubricating additives for drilling fluids are prepared from semi-solid highly viscous and/or high molecular weight lubricants, such as polyalkylenes (e.g., polybutene), by steam jet cooking a mixture of starch, water, and the lubricant in order to uniformly suspend micrometer-sized lubricant droplets in an aqueous starch matrix. These additives avoid the need for toxic emulsifiers, surfactants, or short-chain hydrocarbon solvents for dispersing the lubricants. They impart lubricity to drilling fluids (muds) and also inhibit fluid loss in geological formations by enhancing the filtration control properties of the fluid.

1. Field of the Invention
This invention relates to the use of compositions comprised of starch and semi-solid, highly viscous and/or high molecular weight lubricants having a pour-point within the range. of about 20xc2x0 C. to about xe2x88x9225xc2x0 C. as additives in drilling fluids. Compositions are prepared by a continuous steam jet cooking process that is carried out in the complete absence of surfactants or emulsifiers. Starch is dissolved in water during the jet cooking process; and a water-immiscible (oil-based; oleaginous-based) lubricant is reduced to micron-sized droplets that remain suspended in the starch-water matrix and do not separate or coalesce, even after the dispersion is dried. Dried compositions are easily dispersed in water and impart improved lubricity to drilling fluid compositions. Uncooked, granular special functional starches, e.g. high-temperature fluid-loss starches, may also be blended into these compositions before drum drying to enhance fluid loss properties.
2. Description of the Prior Art
Starch is a high molecular weight natural polymer composed of repeating 1,4-alpha-D-glucopyranosyl units (anhydroglucose units or AGU) and is typically a mixture of linear and branched components. The linear component (amylose) has a molecular weight of several hundred thousand, while the molecular weight of branched amylopectin is on the order of several million. Although normal dent cornstarch contains about 25% amylose, commercial cornstarch varieties are available that range in amylose content from 0% (waxy cornstarch) to about 70% (high amylose cornstarch).
Starch occurs in living plants as discrete granules ranging from about 5 to 40 micrometers in diameter, depending upon the plant source. Starch, as isolated in its native state, is insoluble in water at room temperature because of hydrogen bonding between polysaccharide macromolecules and areas of crystallinity within the starch granule. When a water solution of starch is heated, granules initially take up water with limited swelling. Then, at a definite temperature (typically about 70xc2x0 C.), granules swell rapidly and irreversibly; therefore, areas of crystallinity within the granule are lost. The temperature at which this occurs is referred to as the gelatinization temperature.
Near the gelatinization temperature, a measurable percentage of the starch, in particular the amylose component, becomes soluble and diffuses out of the granule matrix. As the temperature is increased beyond about 70xc2x0 C., a greater percentage of the starch becomes soluble. Granules become highly swollen, until, at a temperature of about 90-100xc2x0 C., a viscous dispersion of starch in water is obtained. However, despite the outward appearance of solubility, starch is only partially water soluble and exists largely as highly swollen granules and granule fragments that may be easily separated from starch solution by centrifugation.
True solutions of starch in water are difficult to prepare using conventional cooking techniques and require the application of specialized techniques, such as autoclaving at elevated temperatures and steam pressures. Steam jet cooking is another technique for preparing starch solutions, which is simpler and more economical than autoclaving, and is suitable for continuous processing. Because of these processing advantages, jet cooking has been used for decades to prepare starch solutions for commercial applications. The method of steam jet cooking involves pumping a water slurry of starch through an orifice located in a heating chamber (i.e., hydroheater), where the starch slurry contacts a jet of high-temperature, high-pressure steam. There are two basic steam jet cooker designs used commercially, and these are discussed in an article by R. E. Klem and D. A. Brogly in Pulp and Paper, Vol. 55, 1981, pages 98-103. In the first of these designs (which is referred to as thermal jet cooking) the amount of steam is carefully controlled to achieve complete steam condensation during the cooking process (i.e., little or no excess steam passes through the cooker). In the second of these designs (which is referred to as excess steam jet cooking), the steam entering the hydroheater exceeds the amount required to achieve the required cooking temperature and pressure, thus allowing considerable amounts of excess steam to pass through the cooker along with the cooked starch solution. The intense turbulence caused by the passage of this excess steam through the hydroheater promotes mechanical shearing and degradation of starch molecules, especially those having the highest molecular weight, and it also produces starch solutions with reduced viscosity (see Dintzis and Fanta, Journal of Applied Polymer Science, Vol. 62, 1996, pages 749-753). The high degree of turbulence and mechanical shear of the excess steam jet cooking process also converts the water-immiscible lubricant phase to a homogeneous aqueous dispersion of micrometer-sized oleaginous droplets. These unique aqueous starch-oil dispersions form the basis for the lubricant compositions of this invention.
An inherent property of starch pastes and solutions is their tendency to form gels on cooling, and this property is commonly referred to as retrogradation. Retrogradation is caused by aggregation of starch molecules through hydrogen bonding and crystallization. The tendency of starch solutions to retrograde and form gels increases with the amylose content of the starch, because amylose is a straight chain polymer with little or no branching. Although retrogradation has also been observed in amylopectin solutions, retrogradation is much slower with amylopectin, and is generally observed only after solutions have been allowed to stand for prolonged periods of time.
U.S. Pat. Nos. 5,676,994 and 5,882,713, which are herein incorporated by reference, describe the preparation of starch-oil compositions by mixing starch, water and oil at room temperature and then passing this mixture through an excess steam jet cooker. The resulting jet cooked compositions are stable with respect to separation and coagulation of oil droplets and are comprised of microscopic droplets of oil, about 1-10 micrometers in diameter, uniformly distributed in the starch-water phase. No emulsifying agents, dispersing agents or surface-active agents are used in the process. The amount of oil in these formulations normally does not exceed about 50% of the total product, and preferred compositions are comprised of about 20-40 parts of oil per 100 parts of starch (17-29% oil, by weight). If the oil content is held within this preferred range, jet cooked compositions are easily dried, using techniques such as drum drying, to yield outwardly dry, flake-like products that can be easily reduced in size by milling, and that exhibit no separation of oil from the dried starch matrix. The dried, jet cooked compositions hydrate rapidly and are easily dispersed in water to form smooth, stable, lump-free dispersions that are similar in properties and appearance to undried dispersions freshly collected from the jet cooker. Water dispersions do not phase separate into their oil and aqueous components on prolonged standing because of a thin layer or shell of starch that spontaneously forms around each oil droplet during the jet cooking process. Scanning electron micrographs of these thin starch shells and possible reasons for their formation are discussed in an article by Fanta et al. in Carbohydrate Polymers, Vol. 39, 1999, pages 25-35.
When oil and gas wells are drilled, fluid formulations with a multitude of properties, including lubricity, are pumped down the well through the drill string and out through nozzles in the drill bit, so that the drilling fluid circulates upward through the annular space between the rotating drill string and the rock formation. The functions of these drilling fluids or xe2x80x9cmudsxe2x80x9d are to cool and lubricate the bit and drill string, to carry the cuttings from the drilling process to the surface, to control and reduce fluid loss into the rock formations, and to support and protect the bore hole until the metal casing can be cemented in place (i.e., create a stable hole). Drilling fluid systems designed to alleviate problems associated with bore hole instability in shale are described in U.S. Pat. No. 5,925,598 (Mody and Fisk, Jr.).
Drilling fluids must also be economical and must not endanger the health and safety of personnel or be a burden to the environment. Mud lubricity (to achieve minimum torque and drag) and mud toxicity (for wells in environmentally sensitive areas, such as offshore drilling) are major concerns when selecting a drilling fluid formulation. Most drilling fluids may be grouped into two major categories: water-based or oleaginous-based. The majority of drilling fluids used today are water-based, i.e., they contain water as the continuous external phase. Although oleaginous-based drilling fluids including the so-called synthetic-based fluids do have performance advantages, drawbacks are higher costs and difficult environmental compliance in specific areas of the world. The lubricant compositions described in this invention are environmentally friendly and are used primarily in water-based drilling fluids.
The lubricity of a drilling fluid is an important factor in the economics of well drilling and is measured by determining the effect of the fluid upon the coefficient of friction between a moving part, such as the drill string, and a surface in contact with the moving part. The lower the coefficient of friction, the greater the lubricity. The lubricity of a drilling fluid determines the fluid""s ability to lower torque and drag forces during the drilling operation and increases the speed of drilling approaching the high rate of penetration observed with the continuous phase oleaginous fluids. Organic, oil-based lubricants are often added to water-based drilling fluids to reduce the coefficient of friction. Reduction of friction during drilling is particularly important in drilling operations where the well bore is not vertical. Emulsifiers or surfactants are typically added to drilling fluids to keep these oil-based, water-insoluble lubricant components suspended as droplets in the water-based fluids and to prevent their separation and coalescence. These emulsifiers can increase the toxicity and irritation level of the fluids.
The following patent documents are examples of prior art related to the addition of water-immiscible liquid lubricants to water-based drilling fluids to enhance their lubricity:
U.S. Pat. No. 5,945,386 (Alonso-DeBolt et al.) describes glycol and glycol ether products, preferably comprising the reaction product between 2-ethylhexanol and the epoxide of 1-hexadecene. These products enhance the lubricity of water-based drilling fluids. When they are used as spotting fluids, they reduce the time required to release stuck pipe.
U.S. Pat. Nos. 5,942,467 and 5,843,872 (Rayborn, Sr. and Rayborn) describe a drilling fluid composition prepared from a carbon black/asphaltite/lignite mixture and a fish oil/glycol mixture. Surfactants are added to these compositions.
U.S. Pat. No. 5,869,434 (Mueller et al.) describes the use of linear hydrocarbon compounds, unsaturated in the alpha position, as the oil phase or as part of the oil phase in drilling fluid formulations. Emulsifiers are used in these water-based formulations.
U.S. Pat. Nos. 5,851,958 and 5,605,879 (Halliday and Schwertner) describe the use of olefinic hydrocarbons as lubricants, rate of penetration enhancers, and spotting fluids in water-based drilling fluids. Spotting fluids preferably include functional additives, such as emulsifiers, viscosifiers, surfactants, and/or brine.
U.S. Pat. No. 5,837,655 (Halliday) describes the use of purified paraffins, selected from the group consisting of white oils and food grade paraffins, as lubricants, rate of penetration enhancers, and spotting fluids in water-based drilling fluids. When used in spotting fluids, paraffins are supplemented with additives such as emulsifiers, viscosifiers, surfactants, and/or brine. When used as lubricants and/or rate of penetration enhancers, the paraffins are preferably used alone or in combination with surfactants.
U.S. Pat. No. 5,707,940 (Bush and Jahnke) relates to oil-in-water drilling fluid formulations comprising brine, at least one triglyceride, at least one alcohol, at least one emulsifier, and at least one sulfurized composition.
U.S. Pat. No. 5,700,767 (Adams) describes a lubricant system comprising surfactant (preferably aluminum stearate), viscosifier (oil-compatible bentonite or polyacrylamide), filming amine, activator (petroleum solvent, coconut oil, terpene, xylene, mineral oil, turpentine, d-limonene or mixtures thereof), and diluent (diesel fuel, fuel oil, gasoline, naphtha, kerosine, or jet fuel). When the lubricant formulation is dispersed in the drilling fluid, the filming amine coats the metal; and friction associated with the drilling operation causes formation of a lubricious emulsion.
U.S. Pat. No. 5,593,954 (Malchow, Jr.) describes drilling fluid compositions containing a mixture of brine, an oil-soluble friction modifier, and an emulsifier. An oil carrier may be used in combination with the friction modifier and emulsifier to form the final oil phase.
U.S. Pat. No. 5,587,354 (Duncan, Jr.) describes a drilling fluid additive comprising a monocyclic terpene (e.g., d-limonene) and an oil, such as mineral oil or vegetable oil. The additive is mixed into a water-based drilling fluid in the range of 1-8% by volume and provides improved rate of penetration, high lubricity and low toxicity.
U.S. Pat. No. 5,248,664 (Hale and Blytas) describes water-based drilling fluid formulations that contain an alcohol such as glycerol to depress the freezing point of the formulation, to inhibit the formation of gas hydrates, to prevent shale dispersion, and to reduce drilling fluid loss. Oils are added to the formulation to increase lubricity, and emulsifiers are used to keep the water-insoluble oils uniformly suspended in the water phase.
U.S. Pat. No. 4,517,100 (Nance and Calkins) describes water-based drilling fluids containing a lubricant composition comprised of a chlorinated component (chlorinated normal paraffins, chlorinated esters of fatty acids, chlorinated waxes, chlorinated olefins, or mixtures thereof) and a sulfurized component (sulfurized fatty acid, sulfurized fatty acid esters, sulfurized polymerized fatty acids, sulfurized olefins, or mixtures thereof).
U.S. Pat. No. 4,409,108 (Carney et al.) describes lubricants for water-based drilling fluids that contain up to about 5% (by weight) of an additive comprising a mixture of an odor-masking agent, a low molecular weight alcohol, and an ester of oleic acid.
U.S. Pat. No. 4,181,617 (Elrod et al.) describes an aqueous drilling fluid containing a lubricant consisting essentially of the reaction product of a fatty vegetable oil with 4,4xe2x80x2-thiodiphenol.
U.S. Pat. No. 3,761,410 (Mondshine et al.) describes water-based drilling fluids prepared by incorporating vegetable oils, animal fats, fatty acids, fatty acid esters, fatty amides and their sulfurized or sulfated reaction products. Formulations also contain a water-insoluble alcohol having 4-15 carbon atoms.
In addition to liquid lubricants, micrometer-sized solid particles or beads may also be added to water-based drilling fluids to increase their lubricity. Some representative examples of this type of lubricant system are: (1) Abrasion- and fracture-resistant, thermally stable and chemically inert ceramic spheres (U.S. Pat. No. 5,792,727, to Jacobs); (2) Plastic beads, for example, those made from a copolymer of divinyl benzene and styrene (U.S. Pat. No. 4,369,655, to Scearce; U.S. Pat. No. 4,063,603, to Rayborn); (3) Plastic-coated magnetic particles in bead form, to facilitate the removal and recycling of these bead compositions (U.S. Pat. No. 4,269,279, to House); (4) Chemically-resistant, lime-silica glass beads (U.S. Pat No. 4,123,367, to Dodd); (5) Resilient graphitic carbon particles (U.S. Pat. No. 5,826,669, to Zaleski et al.); (6) Cellulose, peat or bagasse, containing absorbed oil-based liquid lubricants (U.S. Pat. No. 4,356,096, to Cowan et al.); (7) Mixtures of graphite, silicate and silicone materials (U.S. Pat. No. 5,401,719, to DeBeer).
In many drilling operations, pores and fractures in permeable geological formations can allow drilling fluid to escape or filter into the areas surrounding the subterranean borehole. Fluid loss is reduced when an impervious filter cake is deposited on the sides of the bore hole, and the thickness of this filter cake is usually proportional to the volume of fluid lost, i.e., the thinner the filter cake, the lower the fluid loss. Maintaining the diameter of the bore hole being drilled is critical to the success of the drilling operation. If fluid loss is high, the filter cake will be thick, and the desired diameter of the borehole will be reduced, thus increasing frictional forces and increasing the possibility of binding and sticking of the drill string. Additives are commonly added to drilling fluids to minimize and control this loss of fluid, i.e., to provide filtration control. Examples of some commonly used fluid loss additives are bentonite clays, starches, polymers, lignites, and surfactants. Particularly valuable are water-soluble or water-dispersable polymers that are capable of adding some viscosity to a water-based drilling fluid in addition to providing the necessary filtration control. Drilling fluids must have sufficient viscosity to suspend cuttings and weighting materials when circulation of the drilling fluid is stopped. Preferred polymers for these applications are water-soluble starches and their derivatives, water-soluble gums and their derivatives, and water-soluble cellulose derivatives.
The following patent documents are examples of prior art related to the addition of additives to water-based drilling fluids to enhance their fluid loss and rheological properties:
U.S. Pat. No. 5,919,738 (Norfleet et al.) describes aqueous drilling fluids comprising brines that contain water-insoluble hydrated colloidal complexes to improve fluid loss control and rheological properties. Water-insoluble hydrated colloidal complexes are formed when nonionic colloid-forming materials form complexes with the salts of alkaline earth materials (e.g., calcium chloride and/or calcium bromide) that are used to form the brine. Preferred nonionic colloid-forming materials are polyethylene glycols or compounds that contain a high molar concentration of ethylene oxide.
U.S. Pat. No. 5,789,349 (Patel) describes fluid loss control agents for water-based drilling fluids that are prepared by copolymerizing acrylamide with 2-acrylamido-2-methylpropane sulfonic acid (AMPS) in the presence of the cross-linking monomer methylene-bis-acrylamide.
U.S. Pat. No. 5,134,118 (Patel) describes the use of water-soluble polymers prepared from AMPS and N,N-dimethylacrylamide to increase viscosity and improve fluid loss control in water-based drilling fluids.
U.S. Pat. No. 5,009,267 (Williamson et al.) describes fluid loss control additives prepared from blends of two or more modified or cross-linked starches, or blends of one or more natural starches with one or more modified starches.
U.S. Pat. No. 4,822,500 (Dobson, Jr. et al.) describes fluid loss control agents prepared from blends of xanthomonas gum and cross-linked hydroxypropyl starch.
U.S. Pat. No. 4,547,299 (Lucas et al.) describes the use of water-soluble copolymers prepared from N,N-dimethylacrylamide and AMPS as fluid loss control agents. Cross-linking is optional.
U.S. Pat. No. 4,502,964 (Griddings et al.) describes the use of terpolymers prepared from AMPS, N,N-dimethylacrylamide and acrylonitrile as fluid loss additives and rheology stabilizers.
U.S. Pat. No. 4,471,097 (Uhl et al.) describes the use of water-soluble sulfonated polymers containing vinylimidazole for fluid loss control in a high temperature and high calcium water-based drilling fluid.
U.S. Pat. No. 4,652,384 (Francis et al.) describes the use of starches, that are cross-linked to a high degree, as fluid loss control agents at elevated temperatures. The cross-linked starch requires activation at elevated temperature to achieve suitable effectiveness.
U.S. Pat No. 4,422,947 (Dorsey et al.) describes a thixotropic drilling fluid that contains a cross-linked potato starch, a bacterial heteropolysaccharide, and hydroxyethyl cellulose or carboxymethyl cellulose.
U.S. Pat. No. 4,293,427 (Lucas et al.) describes the use of acrylamide-AMPS copolymers as fluid loss control agents in water-based drilling fluids. Cross-linking with cationic salts is optionally carried out.
U.S. Pat. No. 4,257,903 (Kucera et al.) describes drilling fluids containing cross-linked polysaccharide derivatives.
U.S. Pat. No. 4,090,968 (Jackson and Hartfiel) describes the use of organic derivatives of starch, such as quaternary ammonium starch derivatives, as fluid loss control additives that are stable at high temperature. These derivatives are prepared by reaction of starch with epichlorohydrin and a tertiary amine.
U.S. Pat. No. 3,956,141 (Walker) describes the addition of cationic starch products to control the fluid loss in aqueous drilling fluids that are saturated with calcium hydroxide and contain high levels of salinity.
U.S. Pat. No. 6,180,571 (Sifferman et al.) describes fluid loss control additives comprising starches which are cross-linked and have a Brabender peak viscosity of about 800-1250 Brabender units after about 40-70 minutes at about 92xc2x0 C. The invention is also directed to cross-linked starches that are spray dried to further improve properties.
Some of the best-performing lubricants for drilling muds are solid, high viscosity and/or high molecular weight polymers and copolymers. These materials tend to be recalcitrant toward dispersing in aqueous drilling mud systems and require the use of relatively short-chain diluents, e.g., C10 hydrocarbon solvents, and/or emulsifiers and surfactants that can have adverse effects on handling safety (low flash point) or can lead to an increased toxicity.
This invention is based upon the discovery that lubricating additives for oil drilling fluids may be prepared with semi-solid, highly viscous and/or high molecular weight lubricants having a pour point within the range of about 20xc2x0 C. to about xe2x88x9225xc2x0 C. by: (A) preparing a mixture of starch, water, and lubricant and passing this mixture through a steam jet cooker to afford a composition comprising micrometer-sized lubricant droplets uniformly suspended in an aqueous starch matrix; (B) optionally adding uncooked starch granules to the warm, jet cooked dispersion; and (C) optionally drying this composition, preferably using a drum drier. Compositions are characterized by the following properties: (1) Starch, water, and lubricant are the only components used in the preparative process, and no emulsifiers, surfactants, or short-chain hydrocarbon solvents are required; (2) the lubricant is homogeneously dispersed in the aqueous starch solution as micrometer-sized droplets that are stable with respect to separation and coalescence; (3) dried compositions are not oily to the touch and may be readily reduced in size by grinding or milling; (4) dry compositions disperse easily in water and produce aqueous dispersions having properties similar to jet cooked lubricant dispersions that have never been dried; and (5) addition of these compositions to drilling fluids imparts lubricity to the drilling fluid and also inhibits fluid loss in geological formations by enhancing the filtration control properties of the fluid.
In accordance with this discovery, it is an object of this invention to provide a novel class of aqueous starch-based lubricant compositions for use as lubricants in drilling fluids (muds).
It is also an object of this invention to provide a novel class of dry, starch-based lubricant compositions, containing about 30% water immiscible lubricant, for use in fluids for drilling oil and gas wells. These dry compositions disperse easily in drilling mud formulations and provide aqueous dispersions having lubricity properties similar to undried jet cooked dispersions.
It is another object of this invention to provide starch-based compositions that function as lubricants in drilling fluids without addition of less desirable hydrocarbon solvents, emulsifiers, or surfactants.
It is a further object of this invention to provide starch-based compositions that not only improve the lubricity properties of drilling fluids, but also inhibit fluid loss by enhancing the filtration control properties of the fluid.
Other objects and advantages of this invention will become apparent from the following discussions.
The compositions of this invention are preferably prepared from unmodified starches obtained from cereal grains, such as corn, wheat and rice, or from root crops, such as potato and tapioca. Mixtures of these starches may also be used. Modified starches may also be used to obtain certain properties not obtainable with unmodified starches. An unmodified starch is one that has not been altered by chemical treatment or reduced in molecular weight by reaction with acids or enzymes. Since cornstarch is the least expensive of all commercially available starches, it is the preferred starch variety for use in this invention.
Starches having amylose and amylopectin components in varying proportions may be used in the preparation of these lubricant compositions. Examples of these are waxy cornstarch having an amylose content of essentially 0%, normal dent cornstarch having an amylose content of approximately 25%, and high amylose cornstarch varieties having amylose contents ranging from about 50% to 70%. Mixtures of these various starches can also be used, as well as mixtures of starch and hydrocolloid gums, such as pectin, guar, locust bean, and xanthan.
The ratio of amylose-to-amylopectin is a major factor in determining the physical properties of these lubricant compositions. For example, aqueous starch solutions tend to thicken and form gels (i.e., retrograde) when they are allowed to stand and cool, and this tendency to retrograde increases with increased amylose content in the starch granule. Moreover, the amount of amylose in the starch granule also affects the dispersibility and solubility of jet-cooked and drum-dried starch products when they are mixed into aqueous fluids. Starch-based lubricants prepared from waxy starch are more easily dispersed than analogous lubricant compositions prepared from amylose containing starches, and water dispersibility and solubility both decrease with increased percentages of amylose in the starch-based composition. The presence of gel particles in these aqueous starch dispersions is often advantageous in drilling fluid formulations, since these particles cause the compositions to function more efficiently as fluid loss inhibitors. Since normal dent cornstarch (which contains about 25% amylose) is the least expensive cornstarch variety and also contains sufficient amylose to produce aqueous dispersions having a significant gel particle content, normal dent cornstarch is the preferred starch for use in preparing the compositions of this invention. Although starch is preferably used in the preparation of these compositions, one may also use cereal flour, which is comprised largely of starch, but also contains the protein components of the cereal grain.
The lubricant component of these starch-based lubricant formulations may be selected from any number of water-immiscible, semi-solid or highly viscous and/or high molecular weight lubricants having a pour point within the range of about 20xc2x0 C. to about -25xc2x0 C. These lubricants are characterized by viscosities in the range of about 700-4500 cSt at 40xc2x0 C., and are known to enhance the lubricity of drilling fluids. Examples of these lubricants include (but are not limited to) long-chain (C16 or greater) saturated hydrocarbons and olefinic hydrocarbons, organic esters, and polyalkylenes, such as polybutene. Other examples of lubricants useful in this invention are certain copolymers of xcex1,xcex2-unsaturated dicarboxylic acid esters and olefinically unsaturated compounds, such as disclosed in U.S. Pat. Nos. 5,176,841 and 5,435,928, both of which are herein incorporated by reference. These copolymers typically have viscosities in the range of 750-4500 cSt at 40xc2x0 C. Lubricants contemplated to be within the scope of the invention must have a molecular weight of at least 280, such as the C20-C24 and also the C24-C28 alkenes. Of course, polymerized short-chain hydrocarbons, such as the aforementioned polyolefin materials and the copolymers of xcex1,xcex2-unsaturated dicarboxylic acid esters and unsaturated compounds would meet these limitations. As previously indicated, one particular advantage of the invention is avoidance of toxic solvents (diluents), emulsifiers, and surfactants that are often used in drilling muds, particularly in conjunction with the high molecular weight, extremely viscous lubricants, including various viscous polyalkylenes, e.g. polybutene. For instance, hydrocarbon solvents or diluents, with an alkyl chain length in the range of C10-C12 are less desirable for safety handling (low flash point) and environmental (aquatic toxicity) considerations. Therefore, hydrocarbons having a chain length of less than 16 carbons are specifically excluded as lubricants for use herein.
Compositions of this invention are prepared from starch and lubricant in the relative amounts cited in U.S. Pat. Nos. 5,676,994 and 5,882,713, which have been incorporated by reference. The amount of lubricant may range from about 5-100 parts per 100 parts of starch (by weight). The upper practical limit for lubricant content of the final composition is dictated by the point at which the water-immiscible lubricant begins to coalesce and separate from the aqueous jet-cooked dispersion. If the starch-lubricant compositions are to be dried (for example, by drum drying), the upper practical limit for the amount of lubricant in the final composition is dictated by the point at which the lubricant separates from starch during the drying process (for example, on the heated drums of the drum drier). Preferred starch-based lubricants for which the advantages of the invention are realized contain about 20 to 50 parts (by weight) of lubricant per 100 parts starch (17-33% lubricant, by weight, in the final dry composition). Higher percentages of lubricant can be used (up to equal parts of starch and lubricant, by weight) when compositions are to be used in the undried state.
The method used to prepare the compositions of this invention is to first prepare a coarse blend of starch, lubricant and water by rapidly stirring together the three components of the mixture at or near room temperature. When the stirrer is stopped, these mixtures tend to separate rapidly into an upper, water-immiscible lubricant phase and a lower phase that consists essentially of starch granules and water. It is therefore desirable to quickly pump the dispersion through the steam jet cooker while it is being stirred in order to minimize separation and loss of expensive lubricant. Passing this coarse dispersion through the steam jet cooker yields a homogeneous dispersion of micrometer-sized lubricant droplets suspended in an aqueous solution of starch. These lubricant droplets do not separate or coalesce, even after prolonged standing. To avoid the problem of separation and possible loss of lubricant prior to cooking, a preferred method of preparation is to (1) jet cook a water slurry of starch; (2) add lubricant to the resulting hot starch solution with high shear mixing; and (3) pass the resulting dispersion a second time through the steam jet cooker. Mixing the lubricant with hot, cooked starch solution prior to final jet cooking stabilizes the dispersion for a sufficiently long time period to allow it to be pumped through the cooker without separation and loss of lubricant. Mixing a small amount of jet cooked and drum dried starch into the coarse, aqueous dispersion of starch granules and lubricant provides a similar level of stabilization.
The pH of the aqueous starch-lubricant dispersion is typically in the 5-7 range, but may be optionally adjusted to any desired range by addition of acid or base. It is well known that the properties of cooked starch are highly dependent upon the pH during cooking. As the pH is reduced to a value lower than about 4, starch will suffer increasing amounts of hydrolytic degradation at the high temperature used for cooking, and the properties of the final product will thus be affected. At a sufficiently low pH, hydrolysis of starch occurs to yield glucose and other water-soluble sugars. The concentration of starch in water during steam jet cooking is typically about 10-25%, by weight; however, the upper limit is variable and is dictated by the desired viscosity of the jet cooked dispersion. Starch concentrations lower than about 10% may also be used; however, with lower solids levels, greater amounts of water must be removed if compositions are to be dried, and the expenses associated with drying will thus be increased.
Cooking is preferably carried out with an excess steam jet cooker (see R. E. Klem and D. L. Brogly, Pulp and Paper, Vol. 55, 1981, pages 98-103) under conditions necessary to attain complete solution in water of both the amylose and amylopectin components of starch. Starch is also reduced in molecular weight by the intense mixing and turbulence that takes place in the hydroheater at the high temperatures and pressures of the jet cooking process. Although no emulsifying or dispersing agents are used in the preparative process, jet cooking converts the lubricant component into micrometer-sized droplets that are homogeneously dispersed throughout the starch solution. Lubricant droplets do not separate and coalesce because of a thin layer or shell of starch that forms spontaneously around each lubricant droplet during the jet cooking process. These starch shells have been isolated and examined using both light microscopy and scanning electron microscopy, and this research has been published by Fanta et al. in Carbohydrate Polymers, Vol. 39, 1999, pages 25-35.
Although jet cooking conditions may be widely varied by one skilled in the art, conditions are typically those cited in U.S. Pat. Nos. 5,676,994 and 5,882,713. Preferred cooking conditions are in the range 130xc2x0-150xc2x0 C. (20-50 psig steam) within the hydroheater portion of the cooker, with a steam line pressure of 65-70 psig entering the cooker. Pumping rate for the aqueous dispersion of starch and lubricant through a laboratory-sized cooker is about 1-liter/minute; however, substantially higher throughputs may be achieved with large, production-scale jet cooking equipment. The instantaneous release of steam pressure as the hot dispersion leaves the cooker results in an immediate temperature drop in the cooked dispersion to 100xc2x0 C.
Drum drying is the preferred method for drying the compositions of this invention. Typical drum drying conditions are 30-70 psig within the drums with a drum rotation speed of about 2-6 rpm. For purposes of this invention, a product is considered to be dry when its water content is less than about 10%. Dry compositions may then be ground, milled, or pulverized to any desired particle size. Other methods of drying, such as spray drying or fluidized bed drying can also be used.
Dispersions produced by this cooking process will contain lubricant droplets having diameters ranging from less than 1-micrometer to about 50 micrometers. Typically, about 90% of these droplets will be under 10 micrometers in diameter. For purposes of this invention, droplets in this size range will be considered as being xe2x80x9cmicrometer-sizexe2x80x9d. Droplet size can be controlled by varying the steam pressure and temperature used in the jet cooking process. For example, higher mechanical shear within the hydroheater, and thus a smaller average droplet size, can be achieved by increasing the steam line pressure entering the cooker. This increases the amount of excess steam passing through the hydroheater and thus increases the intensity of mixing during the jet cooking process. Subjecting cooked dispersions to repeated passes through the steam jet cooker will also decrease average droplet size. The skilled artisan will appreciate the fact that the droplet size range of the compositions of the instant invention are significantly larger than the droplet size of oils that have been emulsified by externally added emulsifiers and surfactants. This larger droplet size may be partially responsible for the excellent lubricating properties of these compositions.
The starch-based drilling fluid lubricants of the invention may be incorporated in the wet or dry state into any water-based or oleaginous-based drilling fluid (mud) as known in the art. The oleaginous-based drilling fluids include the synthetic-based fluids. The amount of dry starch-based lubricant composition added to the drilling fluid will be within the range of about 1-40 lb./barrel (0.1% to 4% v/v water-immiscible lubricant), and preferably 2-10 lb./barrel (0.2% to 1% v/v water-immiscible lubricant).
The starch-based compositions of this invention can also be formulated to inhibit fluid loss and enhance filtration control properties of the drilling fluids to which they are added. These fluid loss and filtration properties are achieved, if a minor amount of granular, uncooked starch is added to the warm (80-85xc2x0 C.), freshly-cooked starch-lubricant dispersion just before it is drum dried. The amount of dry granular starch added is sufficient to provide a final starch-lubricant composition containing 10-20%, and preferably about 15% non-jet cooked starch (by weight) in the total starch-lubricant composition on a dry weight basis. Under these preparative conditions, the added granular starch becomes swollen and gelatinized (but not solubilized), because of the elevated temperature used in the drum drying process (about 130-150xc2x0 C. on the surface of the drums). When the final dried compositions are dispersed in drilling fluids (muds), the added gelatinized starch remains as water-swollen, insoluble particles and thus acts as an impermeable filter cake to inhibit the passage of drilling fluid through porous rock formations.

Starch-containing lubricant systems for oil field applications

The United States of America as represented by the Secretary of Agriculture


A method and device for modulating blood pressure. The method comprises selecting waveforms from a storage area that are representative of body organ function. The selected waveforms are then transmitted to a treatment member, which is in direct contact with the body, and which then broadcasts the waveforms to a target zone to modulate blood pressure. A control module is provided for transmission to the treatment member. The control module contains the waveforms which are selected and transmitted to the treatment member, and computer storage can be provided for greater storage capacity and manipulation of the waveforms.

Hundreds of millions of people in the world suffer some type of detrimental blood pressure condition. In the United States it is estimated that 50 million individuals have hypertension (blood pressure over 140/90). Of these 50 million, only about 27% have their blood pressure controlled by a combination of medication, diet and exercise. Up to age 55, more males have hypertension than females. But after age 55, females catch up and about 75% have hypertension. Hypertension is a risk factor for damage to heart, brain, kidney and eyes. The organs concerned with blood pressure are the brain, endocrine glands, blood vessels (arterial and venous) and the heart.
Low blood pressure (hypotension) also occurs and has different consequences for substantial numbers of people. Some people operate their cardiovascular system at lower than normal pressure with little consequences. These people are often cold in their extremities and can be less energetic than they would be if they operated at usual pressure. Nonetheless, for most people an episode of hypotension can be immediately life threatening if not corrected. Hypotension causes general weakness and faintness because of insufficient blood flow to the brain. Posteriorly low blood is aggravated when a person gets out of bed or stands up quickly, causing syncope (fainting). Hence hypotension is a significant risk factor for falls in the elderly. Hypotension can be idiopathic (of unknown cause) or it can be the result of taking excessive amounts of high blood pressure treatment medications. Losing count of medication doses in the elderly often results in taking a second dose unknowingly. The doubling of a medication dose can result in over-treatment of hypertension and cause serious low blood pressure complications.
A number of medications are regularly and routinely used as a treatment method to lower or raise blood pressure. These medications reach endocrine control areas that can dovetail with the actions of the neural control network. Such medications have a well established place in medical treatment but are always a compromise in attaining the results desired and minimizing side effects.
Although blood pressure can be measured with devices directly implanted in the arterial blood stream most studies use noninvasive methods. Such modern methods encircle finger, wrist or arm by automatic devices that provide blood pressure and pulse rate. Usually blood pressure is measured routinely by a device called a sphygmomanometer which consists of a cuff that is wrapped around the arm and inflated. A stethoscope or microphone is utilized to listen to an artery. As the cuff is deflated the first sound of swishing blood is the systolic blood pressure. When deflation continues and sounds disappear, the diastolic blood pressure is provided. The systolic blood pressure is the pressure attained when the heart contracts and pumps blood throughout the body. The diastolic blood pressure measures the resting pressure on the artery walls between heart contractions.
The arteries are large blood vessels in tubular form that transport blood from the heart. Such arteries branch out into smaller blood vessels called arterioles which deliver blood to the tiniest vessels called capillaries. Such capillaries supply all the body""s organs with blood containing oxygen and nutrients. The arterial network is muscular in nature with the ability to constrict or relax. Generally, constricted arteries raise blood pressure, and those that are relaxed and dilated, lower blood pressure. The arterioles can be constricted and relaxed by the brain to alter blood pressure and change pulse rate.
Arterial blood pulsates at higher pressure and is oxygen rich which gives it the red coloration. Veins containing oxygen-depleted blood are blue in color, and flow at lower pressure. One can visualize the blue blood coursing through veins on the top-side of the hands and other parts of the body surface.
The venous system makes up part of the low-pressure system and serves as a blood reservoir. Veins of the cardiovascular system collect blood from everywhere it has been pumped and then flows it back to the heart. The heart""s right atrium then squeezes blood into the right ventricle which then pumps it to the lungs to exchange carbon dioxide for oxygen. The lungs then supply the oxygen enriched blood to the left atrium for loading into the powerful left ventricle which then circulates that blood via arteries, arterioles and capillaries that span the entire body.
The general term, xe2x80x9cblood pressurexe2x80x9d applies to arterial blood pressure in the circulation system. It fluctuates with each heart beat between a systolic maximum level during contraction and a minimum pressure during its diastolic phase. The geometric mean value is known as the pulse pressure of a human or animal.
Blood pressure is ever changing in response to body organ demands for oxygen, depending on any given organ""s activities. Such oxygen supply must be adequate and not excessive and is supplied by the pumping action of the heart. The rate and tone of heart pumping coupled with the dilation or constriction of blood vessels controls blood pressure. Brain electrical signals coupled with hormone and neurotransmitter chemical action modulate the cardiovascular systems circulatory blood pressure. Some of the neural axons provide neurotransmitter chemicals at their pre-synapses which serves to fine-tune electrical signals as they enter the post-synapse prior to flowing into the heart neuroganglionic plexis and at the blood vessel efferent attachment points. The brain plays a role with its electrical signals for both direct organ control and to signal endocrine organs to produce hormones. Both endocrine and neural signals are in themselves variable so as to modulate responses in answer to overall blood pressure regulatory requirements. This means that there is infinite variability within the collection of available xe2x80x9cbrain stored programs,xe2x80x9d for both the hypothalamus (endocrine) and medullopontine (neural switching) to provide efferent signals to fine-tune blood pressure.
The muscular control of arteries is exterted by the brain based on afferent nerve information on the status and need for more or less pressure by the various body organs. The brain also can constrict any severed ends of an artery to lower blood loss. Such is an example of how finite brain signals control vascular network activity. Neuron axon synapses can introduce chemical neurotransmitters at their gaps to modulate the traveling electrical signals before they instruct target organs. Such targets in the case of blood pressure regulation would be the heart and the blood vessels.
The peripheral nervous system conveys afferent (input) sensory information to the central nervous system (brain) on body and cardiovascular status. The role of the brain, then, is to compare such afferent data with stored information, and then to respond with efferent nerve impulse signals to modulate performance of the cardiovascular system (heart and blood vessels).
The brain is an organ with information integrating function, organ coordinating and instructional output ability. The spinal cord is an extension of the brain. The upward ascending brain structures include the medulla oblongata and then the pons followed by the mesencephalon (mid-brain) and cerebellum before reaching the diencephalon where the hypothalamus and the large cerebral hemispheres are located. The first three structures make up the brain stem and are the processing and control centers for blood pressure. The principal actors in blood pressure control are the medullopontine region and the hypothalamus.
It has been established that the electrical action for regulating cardiovascular blood pressure emerges from the medullopontine area via the vagus nerve bundle. The vagus nerve bundle contains both afferent and efferent nerves that travel long distances to numerous organs. The medullopontine area is keenly interactive with the body it lives in, to insure that the basic life functions are operating and keeping with their original purpose. All organs, including the brain, require continuous oxygen transport by the blood stream to occur at sufficient speed and volume to do the job. Therefore, the brain gives high priority to adjusting cardiovascular performance so as not to injure any body organ because of insufficient or untimely oxygen. The brain itself is more sensitive than all the organs to hypoxia. Hypoxia is inadequate availability of oxygen from the blood stream. Brain cells begin to die in a few minutes, and in 10 minutes without oxygen, death is certain.
The brain""s electrical signals are encoded via specific waveforms but such electrical signals are modified at synaptic gaps located at the junction of the nerve axon and the effector organ. All of this modification is a fine-tuning process that is even influenced by end organ local events. Endocrine gland secretions and neurotransmitter chemicals available at the synaptic gaps can and do alter the received brain signal to meet body demands. Feedback from numerous afferent sensors provide information and action from the endocrine system to modulate the efferent signals at or prior to arrival at the organs regulated. Actual instructions (brain signals) to any particular target organ almost always require modulation because of life continuum demands with their ever changing performance and environmental pressures.
Blood vessels are muscles which are constricted or dilated to provide correct blood circulation performance. As part of this performance, control of the heart is also modulated as to beat rate and myocardial contractile tone. Information sent to the brain regarding performance status is provided by afferent sensors that span the body. Such afferent sensors can be chemical, mechanical, thermal and pressure receptors that provide minute low voltage informational signals to the brain. Such signals can be from outside the body as provided by auditory or visual afferent sensors or internal sensors located within the cardiovascular system and elsewhere. Computations made within the medullopontine region of the brain develop xe2x80x9cmost probablexe2x80x9d output efferent signal instructions after considering afferent sensors information. This goes on as a continuous cardiovascular modulation process throughout life. In addition to the electrical signals from the brain, neurotransmitter hormones produced at nerve synapses or the endocrine system modulate blood pressure.
As the heart contracts and pumps blood (systole), the arteries stretch and store potential energy. When the heart relaxes (diastole) the arteries rebound and keep the blood flowing. This is called the xe2x80x9cwindkesselxe2x80x9d effect and assures continuing circulation to supply of oxygen and nutrients to all parts of the body between heartbeats (contractions).
Regulation of the cardiovascular circulatory system ensures that the entire body is provided with enough blood, not only when at rest but also in situations of extreme exertion or danger. This system can redistribute blood flow to critical organs or deny it to organs that can get by on less flow for a while. For example, digestion causes larger blood volume to the gastrointestinal system. But if an emergency occurs digestion is put on hold and the blood is redirected to the brain or muscles. When the emergency is over the blood flow is returned to the task of digestion.
Regulation of blood flow to the various organs is mainly achieved by alterations in the diameter of the blood vessel lumen (inside bore). The lumen can be incrementally constricted or dilated as required. This lumenal control is accomplished by chemical effects and neural instructions coming from the brain. Blood vessels consist of smooth muscle and contain electrically active cells that continually vary between constriction and relaxation. Nervous control of the blood vessels is mediated with only a few exceptions by the sympathetic nerves of the autonomic nervous system. The autonomic nerves are regulated without conscious participation of the individual. The diencephalon, including the thalamus is an important switch point for the various sensory inputs from eyes, ears and skin as well as other parts of the brain. The diencephalon also houses the hypothalamus which plays an important role in the integration of the nervous system and the endocrine system. Modern oral and injectable medications that improve blood pressure, function largely through endocrine aspects. Neurological performance factors (and tolerates) the presence of cardiovascular medications to balance blood pressure.
Central control of the circulation system is effected by the medullopontine region of the brain. This is a critical part of the brain because its span of control stretches across not only the cardiovascular system, but also the respiratory and digestive functions. The medullopontine region is located at the top of the spinal column and consists of the medulla oblongata and the immediately superior pons structure. These particular structures make few mistakes unless there is hemorrhage, physical damage or malignancy that crosses critical pathways. Most of the life support control of the human or animal body is via the vagus (or tenth cranial) nerve that exits from the medulla oblongata. This nerve is actually a long bundle of afferent and efferent neurons that travels over the internal body to most organs. The vagus nerve emerges from each side of the medulla and travels different routes to the same target organs. Paralysis or severing the two vagus nerves at the level of the medulla or neck is rapidly fatal. Severing a single vagus nerve at the level of the neck will impair life processes and the physicians attending would certainly have their hands full in sustaining life, but it is possible.
In the arterial high pressure control side there are stretch and pressure receptor afferent nerves from the aorta and carotid arteries to provide key information. In the low pressure venous system stretch and other receptors located in the vena cava, atrial heart chambers and in the left ventricle provide blood pressure pulse rate and filling pressure data to the brains medullopontine. Afferent sensory data which compute into efferent nerve signals back to the cardiovascular system is processed in various nucleus tracts of the medulla oblongata and its olive. Alterations in newly arriving afferent data is compared to existing efferent control output before modulative corrective responses are elicited and sent off to the heart and blood vessels.
An important part of blood pressure regulation requires the participation of the adrenal gland medulla for its production of hormonal chemical signals for the control of blood pressure. The adrenal medulla is a neuro-endocrine transducer wherein electrical impulses from the sympathetic preganglion nerve fibers are transformed into hormonal signals. The principal hormones produced in response to the electrical signals are epinephrine or adrenaline, norepinephrine and noradrenaline. Such hormones are released into the blood stream and are collectively called catecholamines. The hypothalamus is the principal brain center that electrically regulates the adrenal response to mental or physical stress.
The adrenal medulla usually functions at a low level of activity except in situations of physical or psychic stress, where larger quantities of catecholamines are released. Such catecholamines play a part in the postganglionic synaptic nerve endings as well as some synaptic gaps in the brain, especially the hypothalamus. Generally, once the adrenal medulla is turned on electrically to produce hormones in response to stress they circulate for some considerable time (up to about 4 hours) and are a principal cause for elevating blood pressure.
The hypothalamus, located in the brain, has considerable effect on the endocrine system and is intimately connected with the pituitary gland which can secrete hormones into a blood portal for fast entry into the blood stream. Electrical afferent signals play a significant role in setting off the hormone releases in the endocrine system. When the afferent nerves signal the hypothalamus that the mental or physical stress is reduced then stimulation of catecholamines reduces and return to normal function. Therefore, it is possible to broadcast countermanding signals to afferent nerves to change blood pressure by tricking the autonomic regulating factors.
The invention provides a method for modulating blood pressure. Stored waveforms representative of waveforms that are generated and carried in the body are selected from a storage area. The selected waveforms are then transmitted to a treatment member which is in direct contact with the body. The treatment member then broadcasts the selected waveforms to an organ in the body.
The waveforms may be selected from a storage area in a computer, such as a scientific computer. The process of transmitting the selected waveforms can either be done remotely or with the treatment member connected to a control module. The transmission may be seismic, electronic, or via any other suitable method.
The invention further provides an apparatus for modulating blood pressure. The apparatus includes a source of collected waveforms that are indicative of body organ functioning, a treatment member formed to be in direct contact with the body, means for transmitting collected waveforms to the treatment member, and means for broadcasting the collected waveforms from the treatment member to a body organ.
The transmitting means may include a digital to analog converter. The source of collected waveforms preferably comprises a computer which has the collected waveforms stored in digital format. The computer may include separate storage areas for collected waveforms of different categories.
The treatment member may be comprised of an antenna or an electrode, or any other means of broadcasting one or more waveforms directly to the body.

Device and method to modulate blood pressure by electrical waveforms